In an apparatus for extracorporeal blood treatment, for example in a dialysis machine, it is the function of a peristaltic pump to convey a defined volume of a medium, such as blood or dialysis solution, by deforming and pinching off an elastically deformable fluid line from a negative pressure side (low-pressure side) to a positive pressure side (high-pressure side). Known peristaltic pumps in said medical apparatuses usually comprise a rotor, a pump casing and the elastic tube line disposed between the rotor and the pump casing as a fluid line. The rotor is coupled to a drive axle of the machine with a fixed torque, is driven by said drive axis and supports pressing elements, e.g. in the form of pressing rollers, adapted to be positioned in the radial direction and being biased against the tube line and the pump casing by compression springs.